1. Field of the Invention
The present invention relates to an intercom system capable of communication with an external terminal device via a communication line, and particularly to an intercom system equipped with an emergency-call mobile phone and operable to automatically transmit a notification to the external terminal device in response to a call from the emergency-call mobile phone.
2. Description of the Related Art
Conventionally, an intercom system comprising a master unit and a plurality of slave units within a residence, a door phone installed, for example, at the entrance has been widely used in a residential application. The intercom system is principally intended to allow mutual communication between terminal devices. For example, in the intercom system, a visitor presses a call button on the door phone to signal a master phone or a slave unit and then the visitor talks to a resident, or residents talk to each other using the master unit and the slave unit.
Further, another intercom system is configured so that for example, a handicapped elderly person uses an emergency-call mobile phone for emergency purposes in his/her own home to call the other terminal device such as a master unit or slave unit when he/she is in an emergency situation, e. g., poor health. The emergency-call mobile phone is very simply configured to only have, for example, a call button and a microphone/speaker and is designed for the purpose of primarily calling a master unit or slave unit, and in this case, the other terminal device is not to be used to call the emergency-call mobile phone.
Moreover, in recent years, still another intercom system has been developed which is operable to receive signals from various sensors and inform a resident of an emergency in response to the signals from said sensors for the purpose of improving security of the resident's home, i. e., which has a function of issuing an alarm in response to fire or gas detection signals output from said sensors.
Patent document 1 suggests a technique for monitoring detection signals output from security sensors and transmitting an alarm signal from an alarm generation unit when it is determined the detection signals indicate an abnormal condition, and then, forwarding the alarm signal to an external terminal device such as a cellular phone, PHS. Further, Patent document 2 suggests a technique for allowing a master unit to inform a previously determined contact (e. g., an external terminal device such as a cellular phone) of an emergency in the event an abnormal condition is detected in the voice of a person who records his/her message using a microphone on a master unit or a slave unit.
Additionally, it is also contemplated that a known emergency-call mobile phone is incorporated in the above techniques so that an emergency-call mobile phone is used to call a master unit or slave unit, which in turn transmits a notification, indicating a resident is in an emergency situation (e. g., resident's illness suddenly becomes worse), to the external terminal device.
[Patent Document 1]
Japanese Unexamined Patent Publication No. 2000-299740
[Patent Document 2]
Japanese Unexamined Patent Publication No. 2004-112387
However, according to the above two conventional techniques, the master unit is able to transmit a notification, indicating a resident is in an emergency situation within his/her residence, to the external terminal device and a owner of the external terminal device does not necessarily respond to that notification, i. e., an answering machine message is in some cases returned to the master unit. Moreover, when the owner of the external terminal device is in such a situation that he/she cannot respond to the notification using his/her phone, in some cases, he/she once establishes speech communication with the master unit and then immediately disconnects the communication. Under such a situation, the intercom system determines the notification has been successfully received by the owner of the terminal device. Therefore, in practice, the notification is in some cases not properly received by the owner of the external terminal device.
Moreover, when an answering machine message is returned from the external terminal device, a voice message from the master unit will be recorded on the terminal device and in this case, an emergency message from the master unit is played during the time the answering machine message (e. g., “I'm not in right now. Please leave your name, phone number, and a message at the sound of the beep”) is playing back. This would obviously be a problematic situation in which the emergency message is not properly recorded on the telephone answering machine occurs.
In particular, when a call is transmitted from the emergency-call mobile phone, in many cases, a real-emergency situation occurs and therefore an emergency notification should be securely received by the external terminal device. Further, even in a case where the emergency message is recorded on the telephone answering machine, it is recommended that the resident of interest is able to directly contact the owner of the external terminal device.
An object of the invention is to provide an intercom system capable of allowing an emergency notification to be received securely and properly by a contact person, so that upon reception of a call from an emergency-call mobile phone, the call is automatically forwarded to previously determined contacts and transmission/notification processes are performed on the contacts in response to how the contacts respond to the call.